The present invention relates to an image processing circuit and a printing apparatus.
Generally, an usual electrophotographic printing apparatus (a printing apparatus such as a printer and a multi-function printer for performing a print operation) executes a screen process of referring to index values for every one pixel unit while searching the pixels in a raster direction, and of obtaining output gradation values from a gamma table and input gradation values corresponding to the index values, with respect to image data (image data generated by CPU on the basis of image data and data sent from PC) to be processed at the time of printing. Since the screen processes having the same contents as described above is easily embodied as hardware, the usual electrophotographic printing apparatus is also configured as an apparatus (an apparatus in which the screen process is executed not by CPU but by an image processing circuit) in which an image processing circuit for executing the screen process is equipped.
In such a electrophotographic printing apparatus, there is an apparatus (for example, see Japanese Patent Publication No. 2006-25220A) for executing not the screen process having the content as described above but a screen process using a method of generating dot growth from the center of gravity position of a cell while storing the sum total of gradation values of the entire cells, by obtaining the center of gravity position of the gradation value for each pixel unit as shown in FIG. 7, in order to be compatible between gradation capability and high resolution. However, since there has not been developed an image processing circuit capable of executing the aforementioned screen process (hereinafter, it is referred to as an AAM screen process) at a speed without any problem in practical use, the usual printing apparatus is configured as an apparatus in which a CPU having comparatively high performance is equipped, in view of circumstances that the AAM screen process is executed in the CPU.